Democratic presidential hopeful Bernie Sanders has rocketed past longtime front-runner Hillary Clinton in New Hampshire, a stunning turn in a race once considered a lock for the former secretary of state, a new Franklin Pierce University/Boston Herald poll shows.

Sanders leads Clinton 44-37 percent among likely Democratic primary voters, the first time the heavily favored Clinton has trailed in the 2016 primary campaign, according to the poll of 442 Granite-Staters.

Vice President Joe Biden got 9 percent support in the test primary match-up. The other announced Democrats in the race, former Maryland Gov. Martin O'Malley, former Rhode Island Gov. Lincoln Chafee and former Virginia Gov. Jim Webb, barely register at 1 percent or below.

The live interview phone poll was conducted Aug. 7-10 and has a margin of error of plus or minus 4.7 percentage points.

Clinton is still viewed overwhelmingly by voters as the likely Democratic nominee, but the results suggest she faces an unexpectedly difficult fight to prevent an embarrassing opening loss in the first-in-the-nation primary.